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  • 1501.
    Utas, Josefin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kritikos, Mikael
    Dvinskikh, Sergey
    Sandström, Dick
    Åkermark, Björn
    Solid-State Structures with Hydrogen Bonds between Phenol and Imi-dazole as Models for Tyrosine and Histidine in ProteinsArticle in journal (Refereed)
  • 1502.
    Utas, Josefin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kritikos, Mikael
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Sandström, Dick
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Water as a Hydrogen Bonding Bridge between a Phenol and Imida-zole. A Simple Model for Water Binding in Enzymes2006In: Biochimica et Biophysica Acta - Bioenergetics, ISSN 0005-2728, E-ISSN 1879-2650, Vol. 1757, no 12, p. 1592-1596Article in journal (Refereed)
    Abstract [en]

    The X-ray crystal structure of the mono-hydrate of 2,2-bis(imidazol-1-ylmethyl)-4-methylphenol has been determined. Three hydrogen bonds hold water very tightly in the crystal, as determined by deuterium solid-state NMR. The hydrogen bond between the phenolic hydroxyl and water appears to have about the same strength as the direct hydrogen bond to imidazole, suggesting that the structure can be a good model for hydrogen bonds that are mediated by a water molecule in enzymes.

  • 1503.
    van der Werf, Angela
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Transformations of Nitrosoarenes and Alkynyl Enones: Selective Synthesis of Nitrogen-Containing Compounds2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The nitrogen atom plays a unique role in organic chemistry. It is abundantly found in organic materials and is responsible for the activity of many biologically relevant compounds. In this thesis, nitrosoarenes and keto- and pyridyl-substituted enynes are used as convenient starting materials for the selective synthesis of nitrogen-containing compounds.

    Nitrosoarenes are versatile compounds that can undergo a broad range of reactions. The nature of the nitroso group is significantly different from that of related nitrogen-based functional groups and this can be used as an advantage in the development of new methodology. In the first part of this thesis, the para-selective halogenation of nitrosoarenes with copper(II) halides as halogenating reagents is explored. The one-pot transformation of the products to the corresponding nitroarenes and anilines is demonstrated. The use of nitrosoarenes for radical N-perfluoroalkylation is presented in the next chapters. N-Perfluoroalkylation is a relatively new field and only a limited number of reagents and substrates have been employed so far. In this thesis, the stable and convenient Langlois reagent was used to achieve selective N-trifluoromethylation of nitrosoarenes to obtain the corresponding hydroxylamines. Longer perfluoroalkyl chains were investigated as well, but the less stable products were defluorinated to form hydroxamic acid derivatives. These products could be reduced to yield perfluoroalkyl amides.

    Keto- and pyridyl-substituted enynes are starting materials designed to undergo cyclization reactions in the presence of a metal catalyst and a nucleophile. This offers the possibility to obtain a variety of more complex molecular structures in a single step. In the second half of the thesis, the reaction between these starting materials and enamines is explored. A range of cyclopenta[c]furans were synthesized in good yields and with high diastereoselectivities from alkynyl enones and enamines with InBr3 as the catalyst. The enamines were formed in situ in a multicomponent reaction. Pyridyl-substituted enynes are the pyridine analogues of alkynyl enones and were found to form polycyclic indolizines in the reaction with cyclic enamines with AgOTf as a catalyst. Good yields and high to excellent diastereoselectivities were obtained. When the reaction was performed with in situ-generated enamines, different indolizine derivatives were obtained.

  • 1504.
    van der Werf, Angela
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Hribersek, Matic
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Selander, Nicklas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    N-Trifluoromethylation of Nitrosoarenes with Sodium Triflinate2017In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 19, no 9, p. 2374-2377Article in journal (Refereed)
    Abstract [en]

    A highly efficient N-trifluoromethylation of nitro-soarenes is reported. The inexpensive and convenient Langlois reagent (sodium triflinate) is employed as a Ch(3)-radical source in combination with a copper catalyst and an oxidant. N-Trifluoromethylated hychoxylamines are obtained in high yields within 1 h at room temperature. The addition of hydroquinone was found to be instrumental to prevent the formation of side products. The method is high-yielding is scalable, and displays a high functional group tolerance.

  • 1505.
    van der Werf, Angela
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Selander, Nicklas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Para-Selective Halogenation of Nitrosoarenes with Copper(II) Halides2015In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 17, no 24, p. 6210-6213Article in journal (Refereed)
    Abstract [en]

    The para-selective direct bromination and chlorination of nitrosoarenes with copper(II) bromide and chloride is reported. Under mild reaction conditions, a rang of halogenated arylnitroso compounds are obtained in moderate to good yields with high regioselectivity. Additionally, the versatility of the method is demonstrated by the development of a One-pot procedure to obtain the corresponding para-halogenated aniline- and nitrobenzene derivatives.

  • 1506.
    van der Werf, Angela
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zheng, Zhiyao
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Selander, Nicklas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    N-Perfluoroalkylation of Nitrosoarenes with PerfluoroalkanesulfinatesManuscript (preprint) (Other academic)
  • 1507. Vasur, Jonas
    et al.
    Kawai, Rie
    Jonsson, K. Hanna M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Engström, Åke
    Frank, Martin
    Andersson, Evalena
    Hansson, Henrik
    Forsberg, Zarah
    Igarashi, Kiyohiko
    Samejima, Masahiro
    Sandgren, Mats
    Ståhlberg, Jerry
    Synthesis of cyclic β-glucan using Laminarinase 16A glycosynthase mutant from the basidiomycete Phanerochaete chrysosporium2010In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 132, no 5, p. 1724-1730Article in journal (Refereed)
    Abstract [en]

    Glycosynthases are precise molecular instruments for making specifically linked oligosaccharides. X-ray crystallography screening of ligands bound to the 1,3(4)-β-d-glucanase nucleophile mutant E115S of Phanerochaete chrysosporium Laminarinase 16A (Lam16A) showed that laminariheptaose (L7) bound in an arch with the reducing and nonreducing ends occupying either side of the catalytic cleft of the enzyme. The X-ray structure of Lam16A E115S in complex with α-laminariheptaosyl fluoride (αL7F) revealed how αL7F could make a nucleophilic attack upon itself. Indeed, when Lam16A E115S was allowed to react with αL7F the major product was a cyclic β-1,3-heptaglucan, as shown by mass spectrometry. NMR confirmed uniquely β-1,3-linkages and no reducing end. Molecular dynamics simulations indicate that the cyclic laminariheptaose molecule is not completely planar and that torsion angles at the glycosidic linkages fluctuate between two energy minima. This is the first report of a glycosynthase that joins the reducing and nonreducing ends of a single oligosaccharide and the first reported synthesis of cyclic β-glucan.

  • 1508.
    Vazquez-Romero, Ana
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bermejo Gómez, Antonio
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Acid- and Iridium-Catalyzed Tandem 1,3-Transposition/3,1-Hydrogen Shift/Chlorination of Allylic Alcohols2015In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 5, no 2, p. 708-714Article in journal (Refereed)
    Abstract [en]

    A method for the selective synthesis of alpha-chlorocarbonyls from allylic alcohols is presented. The reaction occurs through an acid- and iridium-catalyzed tandem process that combines a 1,3-transposition, a 3,1-hydrogen shift, and a chlorination process, and can be applied to a wide range of alpha-aromatic and heteroaromatic secondary allylic alcohols. Saturated non-chlorinated ketones or other side-products derived from overchlorination were not detected.

  • 1509.
    Verboom, Renzo C.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium(II)-catalyzed intramolecular 1,4-oxyacyloxylation of conjugated dienes2004Doctoral thesis, comprehensive summary (Other academic)
  • 1510. Verendel, J. Johan
    et al.
    Nordlund, Michael
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Selective Metal-Catalyzed Transfer of H2 and CO from Polyols to Alkenes2013In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 6, no 3, p. 426-429Article in journal (Refereed)
  • 1511. Verendel, J. Johan
    et al.
    Pamies, Oscar
    Dieguez, Montserrat
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Univ KwaZulu Natal, Sch Chem, Durban, South Africa.
    Asymmetric Hydrogenation of Olefins Using Chiral Crabtree-type Catalysts: Scope and Limitations2014In: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 114, no 4, p. 2130-2169Article, review/survey (Refereed)
  • 1512.
    Verho, Oscar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Transition metal-catalyzed hydrogen transfer processes2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The first part describes the synthesis of new analogues of Bäckvall’s catalyst with varying electronic properties and their application in the racemization of sec-alcohols. The racemization involves two key steps: (i) β-hydride elimination (dehydrogenation of the alcohol) and (ii) hydride re-addition to the intermediate ketone. The obtained results confirmed our previous theory that the electronic properties of the substrate determine which of these two steps that is rate-determining. Furthermore, it was demonstrated that a dramatic increase in racemization rate could be obtained by matching the electronic properties of catalyst and substrate.

    The second part describes mechanistic studies done on Bäckvall’s catalyst, where the exchange of carbon monoxide was investigated. By monitoring the uptake of 13C-labeled CO by 13C NMR spectroscopy, we could observe that the CO-exchange was approximately 20 times faster in the catalytically active tBuO-species than in the chloride precatalyst. Furthermore, an inhibitory effect could be observed in the racemization reaction of (S)-1-phenylethanol upon addition of CO. These results provide strong experimental support for reversible CO dissociation as a key step in the racemization mechanism of sec-alcohols.

    The third part describes the synthesis and characterization of highly dispersed palladium nanoparticles immobilized on amino-functionalized siliceous mesocellular foam. The catalyst exhibited high activity in the aerobic oxidation of a wide range of primary and secondary alcohols, when using air as source of oxygen. Moreover, the catalyst exhibited excellent recyclability and negligible leaching, making it an environmentally friendly alternative for these transformations.

  • 1513.
    Verho, Oscar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Transition Metal-Catalyzed Redox Reactions: A Journey from Homogeneous Ruthenium to Heterogeneous Palladium Catalysis2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The first part of the thesis covers the development and utilization of electronically modified (pentaarylcyclopentadienyl)Ru-complexes in the racemization of secondary alcohols. This study revealed that the electronic properties of the substrate were the main factors dictating whether β-hydride elimination or hydride re-addition becomes the rate-determining step of the racemization process. With this knowledge in hand, it proved to be possible to design more efficient racemization protocols by matching the electronic properties of catalyst and substrate.

    The second part describes mechanistic work that aimed at elucidating the role of CO dissociation in the mechanism of secondary alcohol racemization catalyzed by a (pentaarylcyclopentadienyl)Ru-complex. From CO exchange studies, we demonstrated that CO dissociation occurred in the catalytically active tert-BuO-species as well as in the chloride precatalyst. Furthermore, an inhibition study showed that an increase of the partial pressure of CO had a negative influence on the racemization rate. Together, these two observations provide strong support for CO dissociation as a key step in the racemization of secondary alcohols.

    The third part concerns the improved synthesis and characterization of a heterogeneous catalyst consisting of Pd nanoparticles immobilized on aminopropyl-functionalized siliceous mesocellular foam. The developed Pd nanocatalyst was found to be a highly efficient and recyclable catalyst for the aerobic oxidation of a wide range of primary and secondary alcohols to the corresponding aldehydes and ketones.

    The fourth part deals with the successful application of the Pd nanocatalyst in chemically-induced H2O oxidation, when using either ceric ammonium nitrate or [Ru(bpy)3]3+ as the terminal oxidant. Remarkably, the Pd nanocatalyst proved to catalyze this reaction with high efficiency and the measured TOF was found to greatly exceed those of current state-of-the-art metal oxide catalysts.

    The fifth and final part describes the co-immobilization of Pd nanoparticles and the enzyme Candida Antarctica Lipase B into the same cavities of mesocellular foam, to generate a “metalloenzyme-like” hybrid catalyst for the dynamic kinetic resolution of a primary amine. The close proximity of the two catalytic species led to an enhanced cooperativity between them and resulted in an overall more efficient tandem process. 

  • 1514.
    Verho, Oscar
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chemoenzymatic Dynamic Kinetic Resolution: A Powerful Tool for the Preparation of Enantiomerically Pure Alcohols and Amines2015In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, no 12, p. 3996-4009Article in journal (Refereed)
    Abstract [en]

    Chemoenzymatic dynamic kinetic resolution (DKR) constitutes a convenient and efficient method to access enantiomerically pure alcohol and amine derivatives. This Perspective highlights the work carried out within this field during the past two decades and pinpoints important avenues for future research. First, the Perspective will summarize the more developed area of alcohol DKR, by delineating the way from the earliest proof-of-concept protocols to the current state-of-the-art systems that allows for the highly efficient and selective preparation of a wide range of enantiomerically pure alcohol derivatives. Thereafter, the Perspective will focus on the more challenging DKR of amines, by presenting the currently available homogeneous and heterogeneous methods and their respective limitations. In these two parts, significant attention will be dedicated to the design of efficient racemization methods as an important means of developing milder DKR protocols. In the final part of the Perspective, a brief overview of the research that has been devoted toward improving enzymes as biocatalysts is presented.

  • 1515.
    Verho, Oscar
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Dilenstam, Marléne D. V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kärkäs, Markus
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johnston, Eric
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Torbjörn
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Application and mechanistic studies of a water-oxidation catalyst in alcohol oxidation by employing oxygen-transfer reagents2012In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, no 52, p. 16947-16954Article in journal (Refereed)
    Abstract [en]

    By using a dimeric ruthenium complex in combination with tert-butyl hydrogen peroxide (TBHP) as stoichiometric oxidant, a mild and efficient protocol for the oxidation of secondary benzylic alcohols was obtained, thereby giving the corresponding ketones in high yields within 4 h. However, in the oxidation of aliphatic alcohols, the TBHP protocol suffered from low conversions owing to a competing Ru-catalyzed disproportionation of the oxidant. Gratifyingly, by switching to Oxone (2 KHSO5KHSO4K2SO4 triple salt) as stoichiometric oxidant, a more efficient and robust system was obtained that allowed for the oxidation of a wide range of aliphatic and benzylic secondary alcohols, giving the corresponding ketones in excellent yields. The mechanism for these reactions is believed to involve a high-valent RuV–oxo species. We provide support for such an intermediate by means of mechanistic studies.

  • 1516.
    Verho, Oscar
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Gao, Feifei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johnston, Eric V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nagendiran, Anuja
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zheng, Haoquan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Mesoporous silica nanoparticles applied as a support for Pd and Au nanocatalysts in cycloisomerization reactions2014In: APL materials, ISSN 2166-532X, Vol. 2, no 11, p. 113316-Article in journal (Refereed)
    Abstract [en]

    Ultra-small mesoporous silica nanoparticles (MSNs) have been synthesized at room temperature with particle sizes ranging from 28 to 45 nm. These MSNs have been employed as heterogeneous supports for palladium and gold nanocatalysts. The colloidal nature of the MSNs is highly useful for catalytic applications as it allows for better mass transfer properties and a more uniform distribution of the nanocatalysts in solution. The two nanocatalysts were evaluated in the cycloisomerization of alkynoic acids and demonstrated to produce the corresponding alkylidene lactones in good to excellent yields under mild conditions. In addition to their high activity, the catalysts exhibit low degree of metal leaching and straight-forward recycling, which highlight the practical utility of MSNs as supports for nanocatalysts. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.

  • 1517.
    Verho, Oscar
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Gustafson, Karl P. J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nagendiran, Anuja
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mild and Selective Hydrogenation of Nitro Compounds using Palladium Nanoparticles Supported on Amino-Functionalized Mesocellular Foam2014In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 6, no 11, p. 3153-3159Article in journal (Refereed)
    Abstract [en]

    We present the utilization of a heterogeneous catalyst comprised of Pd nanoparticles supported on aminopropyl-functionalized siliceous mesocellular foam (Pd-0-AmP-MCF) for the selective hydrogenation of aromatic, aliphatic, and heterocyclic nitro compounds to the corresponding amines. In general, the catalytic protocol exclusively affords the desired amine products in excellent yields within short reaction times with the reactions performed at room temperature under ambient pressure of H-2. Moreover, the reported Pd nanocatalyst displayed excellent structural integrity for this transformation as it could be recycled multiple times without any observable loss of activity or leaching of metal. In addition, the Pd nanocatalyst could be easily integrated into a continuous-flow device and used for the hydrogenation of 4-nitroanisole on a 2.5 g scale, where the product p-anisidine was obtained in 95% yield within 2 h with a Pd content of less than 1 ppm.

  • 1518.
    Verho, Oscar
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johnston, Eric
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Karlsson, Erik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tuning of the Electronic Properties of a Cyclopentadienylruthenium Catalyst to Match Racemization of Electron-Rich and Electron-Deficient Alcohols2011In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, no 40, p. 11216-11222Article in journal (Refereed)
    Abstract [en]

    The synthesis of a new series of cyclopentadienylruthenium catalysts with varying electronic properties and their application in racemization of secondary alcohols are described. These racemizations involve two key steps: 1) β-hydride elimination (dehydrogenation) and 2) re-addition of the hydride to the intermediate ketone. The results obtained confirm our previous theory that the electronic properties of the substrate determine which of these two steps is rate determining. For an electron-deficient alcohol the rate-determining step is the β-hydride elimination (dehydrogenation), whereas for an electron-rich alcohol the re-addition of the hydride becomes the rate-determining step. By matching the electronic properties of the catalyst with the electronic properties of the alcohol, we have now shown that a dramatic increase in racemization rate can be obtained. For example, electron-deficient alcohol 15 racemized 30 times faster with electron-deficient catalyst 6 than with the unmodified standard catalyst 4. The application of these protocols will extend the scope of cyclopentadienylruthenium catalysts in racemization and dynamic kinetic resolution.

  • 1519.
    Verho, Oscar
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kärkäs, Markus
    Åkermark, Torbjörn
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Materials Chemistry.
    Johnston, Eric V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Gustafson, Karl
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Svengren, Henrik
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Well-Defined Palladium Nanoparticles Supported on Amino-Functionalized Siliceous Mesocellular Foam: An Efficient Heterogeneous Catalyst for Chemically-Induced H2O OxidationManuscript (preprint) (Other academic)
  • 1520.
    Verho, Oscar
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nagendiran, Anuja
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johnston, Eric V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tai, Cheuk-wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nanopalladium on Amino-Functionalized Mesocellular Foam: An Efficient Catalyst for Suzuki Reactions and Transfer Hydrogenations2013In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 5, no 2, p. 612-618Article in journal (Refereed)
    Abstract [en]

    The applications of a heterogeneous Pd0-AmP-MCF nanoparticle catalyst in Suzuki cross-coupling reactions and transfer hydrogenations of alkenes are described. The catalyst was highly efficient for both transformations, resulting in 1)coupling of a wide range of aryl halides with various boronic acids in high yields and 2)chemoselective reduction of a variety of alkenes with the use of 1-methyl-1,4-cyclohexadiene as hydrogen donor. Moreover, the catalyst can be recycled several times without any significant decrease in activity or leaching of metal into solution, making the protocol economical and environmentally friendly. In the case of the Suzuki cross-coupling, a 15-fold increase in reaction rate was observed if the reaction was performed under microwave irradiation compared to conventional heating in an oil bath.

  • 1521.
    Verho, Oscar
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nagendiran, Anuja
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johnston, Eric V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nanopalladium on Amino-Functionalized Mesocellular Foam as an Efficient and Recyclable Catalyst for the Selective Transfer Hydrogenation of Nitroarenes to Anilines2014In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 6, no 1, p. 205-211Article in journal (Refereed)
    Abstract [en]

    Herein, we report on the use of nanopalladium on amino-functionalized siliceous mesocellular foam as an efficient heterogeneous catalyst for the transfer hydrogenation of nitroarenes to anilines. In all cases, the protocol proved to be highly selective and favored the formation of the desired aniline as the single product in high yields with short reaction times if naturally occurring and renewable -terpinene was employed as the hydrogen donor. Furthermore, the catalyst displayed excellent recyclability over five cycles and negligible leaching of metal into solution, which makes it an eco-friendly and economic catalyst to perform this transformation. The scalability of the protocol was demonstrated with the reduction of 4-nitroanisole on a 2g scale, in which p-anisidine was isolated in 98% yield.

  • 1522.
    Verho, Oscar
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Pourghasemi Lati, Monireh
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Oschmann, Michael
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    A Two-Step Procedure for the Overall Transamidation of 8-Aminoquinoline Amides Proceeding via the Intermediate N-Acyl-Boc-Carbamates2018In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 83, no 8, p. 4464-4476Article in journal (Refereed)
    Abstract [en]

    Herein a two-step strategy for achieving overall transamidation of 8-aminoquinoline amides has been explored. In this protocol, the 8-aminoquinoline amides were first treated with Boc(2)O and DMAP to form the corresponding N-acyl-Boc-carbamates, which were found to be sufficiently reactive to undergo subsequent aminolysis with different amines in the absence of any additional reagents or catalysts. To demonstrate the utility of this approach, it was applied on a number of 8-aminoquinoline amides from the recent C-H functionalization literature, enabling access to a range of elaborate amide derivatives in good to high yields

  • 1523.
    Verho, Oscar
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zheng, Haoquan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Gustafson, Karl P. J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nagendiran, Anuja
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Application of Pd Nanoparticles Supported on Mesoporous Hollow Silica Nanospheres for the Efficient and Selective Semihydrogenation of Alkynes2016In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 8, no 4, p. 773-778Article in journal (Refereed)
    Abstract [en]

    Herein, the preparation of a heterogeneous catalyst consisting of 1-2nm sized Pd nanoparticles supported on amino-functionalized mesoporous hollow silica nanospheres and its use for the semihydrogenation of mono- and disubstituted alkynes is reported. By utilizing this Pd nanocatalyst together with the green poisoning agent DMSO, high yields of the desired alkenes could be achieved, while suppressing the degree of over-reduction to alkanes. To our delight, the Pd nanocatalyst displayed remarkable chemoselectivity towards the alkyne moiety, allowing the transformation to be carried out in the presence of other reducible functionalities, such as halogens, carbonyl, and nitro groups.

  • 1524.
    Verho, Oscar
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Torbjörn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johnston, Eric V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Gustafson, Karl P. J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Svengren, Henrik
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Kärkäs, Markus D.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Well-Defined Palladium Nanoparticles Supported on Siliceous Mesocellular Foam as Heterogeneous Catalysts for the Oxidation of Water2015In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, no 15, p. 5909-5915Article in journal (Refereed)
    Abstract [en]

    Herein, we describe the use of Pd nanoparticles immobilized on an amino-functionalized siliceous mesocellular foam for the catalytic oxidation of H2O. The Pd nanocatalyst proved to be capable of mediating the four-electron oxidation of H2O to O-2, both chemically and photochemically. The Pd nanocatalyst is easy to prepare and shows high chemical stability, low leaching, and recyclability. Together with its promising catalytic activity, these features make the Pd nanocatalyst of potential interest for future sustainable solar-fuel production.

  • 1525.
    Vesely, Jan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Dziedzic, Pawel
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Aza-Morita-Baylis-Hillman-type reactions: highly enantioselective organocatalytic addition of unmodified alpha-beta-unsaturated aldehydes to N-Boc protected imines2007In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 48, no 39, p. 6900-6904Article in journal (Refereed)
    Abstract [en]

    Highly enantioselective catalytic routes to Boc protected aza-Morita-Baylis-Hiliman-type products are presented. The organocatalytic asymmetric reactions between unmodified alpha,beta-unsaturated aldehydes and N-Boc protected aryl imines proceed with excellent chemo- and enantioselectivity to give the corresponding compounds in good yields with 97-99% ee

  • 1526.
    Vesely, Jan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ibrahem, Ismail
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rios, Ramón
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhao, Gui-Ling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Xu, Yongmei
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Enantioselective organocatalytic conjugate addition of amines to alpha-beta-unsaturated aldehydes: one-pot asymmetric synthesis of beta-amino acids and 1,3-diamines2007In: Tetrahedron Letters, Vol. 48, p. 2193-2198Article in journal (Refereed)
  • 1527. Vesely, Jan
    et al.
    Ibrahem, Ismail
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhao, Guiling
    Rios, Ramon
    Cordova, Armando
    Organocatalytic Enantioselective Aziridination of α,β-Unsaturated Aldehydes2007In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 46, p. 778-Article in journal (Refereed)
  • 1528.
    Vesely, Jan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ibrahem, Ismail
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhao, Gui-Ling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rios, Ramón
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Organocatalytic enantioselective aziridination of alpha,beta-unsaturated aldehydes2007In: Abstracts of Papers, 234th ACS National Meeting, Boston, MA, United States, August 19-23, 2007, 2007Conference paper (Other academic)
  • 1529.
    Vesely, Jan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ibrahem, Ismail
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhao, Gui-Ling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rios, Ramón
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Organocatalytic enantioselective aziridination of alpha,beta-unsaturated aldehydes2007In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 46, p. 778-781Article in journal (Refereed)
  • 1530.
    Vesely, Jan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rios, Ramon
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ibrahem, Ismail
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Highly enantioselective organocatalytic addition of unmodified aldehydes to N-Boc protected imines: one-pot asymmetric synthesis of beta-amino acids2007In: Tetrahedron Letters, Vol. 48, p. 421-425Article in journal (Refereed)
  • 1531.
    Vesely, Jan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rios, Ramón
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Proline and Lewis base co-catalyzed addition of alpha,beta-unsaturated aldehydes to nitrostyrenes2008In: Tetrahedron Letters, ISSN 0040-4039, Vol. 49, no 7, p. 1137-1140Article in journal (Refereed)
  • 1532.
    Vesely, Jan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rios, Ramón
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ibrahem, Ismail
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhao, Gui-Ling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Department of Physical, Inorganic and Structural Chemistry.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    One-pot catalytic asymmetric cascade synthesis of cycloheptane derivatives2008In: Chemistry: a European journal, ISSN 0947-6539, Vol. 14, no 9, p. 2693-2698Article in journal (Refereed)
  • 1533.
    Vesely, Jan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rydner, Lina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Oscarson, Stefan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Variant synthetic pathway to glucuronic acid-containing di- and trisaccharide thioglycoside building blocks for continued synthesis of Cryptococcus neoformans capsular polysaccharide structures2008In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 343, no 12, p. 2200-2208Article in journal (Refereed)
    Abstract [en]

    An alternative pathway to glucuronic acid-containing di- and trisaccharide thioglycoside building blocks, suitable for the synthesis of Cryptococcus neoformans capsular polysaccharide structures, has been developed. As opposed to our earlier synthesis, this approach features the introduction of the glucuronic acid motif at the di- and trisaccharide level through oxidation of a glucose residue. This approach circumvents problems encountered in glycosylations with glucuronic acid donors and benzylation of glucuronic acid-containing derivatives. Selective protection of primary alcohols was obtained at the di- and trisaccharide stage using TBDMS or trityl protecting groups, respectively. After benzylation of the secondary hydroxyl groups and subsequent removal of the TBDMS or trityl group, oxidation of the free primary alcohols to carboxylic acids was performed in high yield using the TEMPO–BAIB reagent mixture, which does not tend to oxidize thioglycosides. The new approach requires a number of extra steps, but has proven to be more reliable and easily reproducible.

  • 1534.
    Vesely, Jan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhao, Gui-Ling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bartoszewicz, Agnieszka
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Organocatalytic asymmetric nitrocyclopropanation of alpha,beta-unsaturated aldehydes2008In: Tetrahedron Letters, ISSN 0040-4039, Vol. 49, no 27, p. 4209-4212Article in journal (Refereed)
  • 1535.
    Vico Solano, Marta
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    González Miera, Greco
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Pascanu, Vlad
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Inge, A. Ken
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Martín‐Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Versatile Heterogeneous Palladium Catalysts for Diverse Carbonylation Reactions under Atmospheric Carbon Monoxide Pressure2018In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 10, no 5, p. 1089-1095Article in journal (Refereed)
    Abstract [en]

    Herein, we report a versatile carbonylation protocol using heterogeneous Pd-0 nanoparticles supported on the metal-organic frameworks (MOFs) MIL-88B-NH2 (Fe/Cr). The synthesis of a vast array of carbonyls, which includes amides, esters, carboxylic acids, and -ketoamides, was achieved through mono- and dicarbonylation reactions. The selectivity could be controlled simply by tuning the reaction conditions. Superior activity and selectivity were recorded in some cases compared to that achieved with commercial Pd/C. However, the utility of an elaborate catalyst support is questionable and important reactivity and recyclability issues are discussed.

  • 1536. Vilchez, Samuel
    et al.
    Lundborg, Magnus
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Urbina, Felipe
    Weintraub, Andrej
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Structural studies of the O-antigenic polysaccharides from the enteroaggregative Escherichia coli strain 94/D4 and the international type strain Escherichia coli O822009In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 344, no 18, p. 2528-2532Article in journal (Refereed)
    Abstract [en]

    The structure of the O-antigen polysaccharides (PS) from the enteroaggregative Escherichia coli strain 94/D4 and the international type strain E. coli O82 have been determined. Component analysis and 1H, 13C, and 31P NMR spectroscopy experiments were employed to elucidate the structure. Inter-residue correlations were determined by 1H, 13C-heteronuclear multiple-bond correlation, and 1H, 1H-NOESY experiments. d-GroA as a substituent is linked via its O-2 in a phosphodiester-linkage to O-6 of the α-d-Glcp residue. The PS is composed of tetrasaccharide repeating units with the following structure:

    →4)-α-d-Glcp6-(P-2-d-GroA)-(1→4)-β-d-Galp-(1→4)-β-d-Glcp-(1→3)-β-d-GlcpNAc-(1→

    Cross-peaks of low intensity from an α-d-Glcp residue were present in the NMR spectra and spectral analysis indicates that they originate from the terminal residue of the polysaccharide. Consequently, the biological repeating unit has a 3-substituted N-acetyl-d-glucosamine residue at its reducing end. Enzyme immunoassay using specific anti-E. coli O82 rabbit sera showed identical reactivity to the LPS of the two strains, in agreement with the structural analysis of their O-antigen polysaccharides.

  • 1537.
    Villo, Piret
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. University of Tartu, Estonia.
    Kervefors, Gabriella
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Olofsson, Berit
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Inside front cover2018Other (Other academic)
  • 1538.
    Villo, Piret
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. University of Tartu, Estonia.
    Kervefors, Gabriella
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Olofsson, Berit
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Transition metal-free, chemoselective arylation of thioamides yielding aryl thioimidates or N-aryl thioamides2018In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 54, no 64, p. 8810-8813Article in journal (Refereed)
    Abstract [en]

    Reactions of secondary thioamides with diaryliodonium salts under basic, transition metal-free conditions resulted in chemoselective S-arylation to provide aryl thioimidates in good to excellent yields. Equimolar amounts of thioamide, base and diaryliodonium salt were sufficient to obtain a diverse selection of products within short reaction times. Reactions with thiolactams delivered N-arylated thioamides in good yield at room temperature.

  • 1539.
    Volkov, Alexey
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Catalytic Amide Reductions under Hydrosilylation Conditions2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis covers the development of catalytic methodologies for the mild and chemoselective reductions of amides. The first part of the thesis describes the use of a Fe(II)/NHC catalyst for the deoxygenation of aromatic tertiary amides to corresponding amines. The protocol is characterized by low catalyst loading, mild reaction conditions and the use of air and moisture stable polymethylhydrosilaxane (PMHS) as the hydride source.

    The second part concerns the development of a protocol for the room temperature deoxygenation of a wide range of tertiary amides to amines using catalytic amounts of Et2Zn and LiCl together with PMHS. The system displayed high levels of chemoselectivity tolerating various reducible groups such as nitro, nitrile, and olefin functionalities, and was shown to be applicable for the reduction of aromatic, heteroaromatic and aliphatic tertiary amides.

    The attempts to expand the scope of the Fe-based protocol to accommodate benzylic tertiary amides led to the development of a transition metal-free catalytic system based on KOtBu for the formation of enamines. The final products constitute an important class of precursors for a wide range of valuable compounds in organic chemistry. Moreover, avoiding the use of transition metals in the protocol allowed the desired products to be obtained without the hazardous metal contaminants.

    The last chapter of the thesis describes the Mo(CO)6-catalyzed hydrosilylation of amides. The Mo-based catalyst was proven to mediate the deoxygenation of α,β-unsaturated tertiary and secondary amides to the corresponding allylamines without reduction of the olefinic bonds. Further development of the catalytic system revealed an unprecedented chemoselectivity in the hydrosilylation of aromatic and certain aliphatic tertiary amides in the presence of a variety of reducible groups along with aldehydes and imines that were tolerated for the first time. Moreover, it was possible to control the reaction outcome by variation of the reaction temperature to obtain either amines or aldehydes as the major products. The synthetic utility of the developed Mo(CO)6-catalyzed protocols was further demonstrated in the synthesis of the pharmaceuticals Naftifine and Donepezil.

  • 1540.
    Volkov, Alexey
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Catalytic Hydrosilylation of Amides2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, different protocols and approaches are described for thehydrosilylation of tertiary amides to amines or enamines. The development of simple andeffective methods for the production of amines from amides is of great importance to bothacademic and industrial users, since the final product represents a valuable building blockfor fine and bulk chemicals. Furthermore, enamines constitute important starting materialsto a variety of functionalized and complex organic compounds.

    The first part of the thesis focuses on the development and investigation of acatalytic protocol for the reduction of amides to amines using an inexpensive and efficientiron catalyst together with cost-effective, stable, and non-toxic PMHS(poly(methylhydrosiloxane)) as the hydride source. The active catalytic species was formedin situ by combining Fe(OAc)2 as the iron source and easily synthesized imidazolium salts.

    The second part deals with a novel transition metal–free catalytic hydrosilylationmethodology for the transformation of amides to the corresponding amines or enamines. Itwas found that nucleophilic activation of the trialkoxysilanes by potassium tert-butoxidefacilitates the reduction of benzylic amides to enamines; aliphatic and benzamides toamines. Furthermore, a simple way to tune the selectivity of the reduction of aliphaticamides was found.

  • 1541.
    Volkov, Alexey
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Buitrago, Elina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Adolfsson, Hans
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Direct Hydrosilylation of Tertiary Amides to Amines by an In Situ Formed Iron/N-Heterocyclic Carbene Catalyst2013In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 11, p. 2066-2070Article in journal (Refereed)
    Abstract [en]

    Tertiary amides were efficiently reduced to their corresponding tertiary amines in high isolated yields by using the commercially available and inexpensive polymeric silane polymethylhydrosiloxane (PMHS) as the reducing agent. The reaction is efficiently catalyzed by an in situ generated iron/N-heterocyclic carbene complex (1 mol-%) obtained from iron(II) acetate and 1-(2-hydroxy-2-phenylethyl)-3-methylimidazolium triflate ([PhHEMIM][OTF]). A catalytic amount of lithium chloride (1 mol-%) present in the reaction mixture significantly reduced the reaction time and increased the chemoselectivity of the reduction process.

  • 1542.
    Volkov, Alexey
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Gustafson, Karl P. J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Verho, Oscar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Adolfsson, Hans
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mild Deoxygenation of Aromatic Ketones and Aldehydes over Pd/C Using Polymethylhydrosiloxane as the Reducing Agent2015In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 54, no 17, p. 5122-5126Article in journal (Refereed)
    Abstract [en]

    Herein, a practical and mild method for the deoxygenation of a wide range of benzylic aldehydes and ketones is described, which utilizes heterogeneous Pd/C as the catalyst together with the green hydride source, polymethylhydrosiloxane. The developed catalytic protocol is scalable and robust, as exemplified by the deoxygenation of ethyl vanillin, which was performed on a 30 mmol scale in an open-to-air setup using only 0.085 mol% Pd/C catalyst to furnish the corresponding deoxygenated product in 93% yield within 3 hours at room temperature. Furthermore, the Pd/C catalyst was shown to be recyclable up to 6 times without any observable decrease in efficiency and it exhibited low metal leaching under the reaction conditions.

  • 1543.
    Volkov, Alexey
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tinnis, Fredrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Adolfsson, Hans
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Catalytic Reductive Dehydration of Tertiary Amides to Enamines under Hydrosilylation Conditions2014In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 16, no 3, p. 680-683Article in journal (Refereed)
    Abstract [en]

    Tertiary amides are efficiently reduced to their corresponding enamines under hydrosilylation conditions, using a transition-metal-free catalytic protocol based on t-BuOK (5 mol %) and (MeO)(3)SiH or (EtO)(3)SiH as the reducing agent. The enamines were formed with high selectivity in good-to-excellent yields.

  • 1544.
    Volkov, Alexey
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tinnis, Fredrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Slagbrand, Tove
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Pershagen, Ida
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Adolfsson, Hans
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mo(CO)6 catalysed chemoselective hydrosilylation of alpha,beta-unsaturated amides for the formation of allylamines2014In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 50, no 93, p. 14508-14511Article in journal (Refereed)
    Abstract [en]

    Molybdenum hexacarbonyl (Mo(CO)(6)) was used as an efficient catalyst for the chemoselective reduction of the amide functionality in alpha,beta-unsaturated compounds, under hydrosilylation conditions using 1,1,3,3-tetramethyldisiloxane (TMDS) as the hydride source.

  • 1545.
    Volkov, Alexey
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tinnis, Fredrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stagbrand, Tove
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Trillo, Paz
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Adolfsson, Hans
    Chemoselective reduction of carboxamides2016In: Chemical Society Reviews, ISSN 0306-0012, E-ISSN 1460-4744, Vol. 45, no 24, p. 6685-6697Article, review/survey (Refereed)
    Abstract [en]

    The reduction of amides gives access to a wide variety of important compounds such as amines, imines, enamines, nitrites, aldehydes and alcohols. The chemoselective transformation into these functional groups is challenging due to the intrinsic stability of the amide bond; nevertheless, the ability to reduce highly stable carboxamides selectively in the presence of sensitive functional groups is of high synthetic value for academic and industrial chemists. Hydride-based reagents such as LiAlH4 or diboranes are today the most commonly used compounds for amide reductions, and apart from the substantial amount of waste generated using these methods, they lack tolerance to most other functional groups. This tutorial review provides an overview of the recent progress made in the development of chemoselective protocols for amide reduction and gives an insight to their advantages and drawbacks.

  • 1546.
    Volla, Chandra M. R.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-Catalyzed Aerobic Domino Oxidative Carbocyclization-Alkynylation of Allenynes2013In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 52, no 52, p. 14209-14213Article in journal (Refereed)
  • 1547.
    Volla, Chandra M. R.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-Catalyzed Oxidative Domino Carbocyclization-Arylation of Bisallenes2016In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 6, no 10, p. 6398-6402Article in journal (Refereed)
    Abstract [en]

    Herein we report a highly efficient and site selective palladium-catalyzed oxidative carbocyclization arylation reaction of bisallenes and arylboronic acids under operationally simple conditions for the selective synthesis of cyclohexadiene derivatives. The palladium source and the solvent proved to be crucial for the selectivity and the reactivity displayed. Interestingly, in the absence of the nucleophile, an oxidative carbocyclization-beta-elimination pathway predominates. The reaction conditions are compatible with a wide range of functional groups, and the reaction exhibits broad substrate scope. Furthermore, key information regarding the mechanism was obtained using control experiments and kinetic studies.

  • 1548.
    Volla, Chandra M. R.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-Catalyzed Oxidative Domino Carbocyclization- Carbonylation-Alkynylation of Enallenes2014In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 16, no 16, p. 4174-4177Article in journal (Refereed)
    Abstract [en]

    An oxidative carbocyclization-carbonylation-alkynylation reaction cascade has been developed using catalytic amounts of palladium(II) salts. The domino reaction proceeds efficiently, giving the corresponding ynones in good to excellent yields under operationally simple conditions. A wide range of aromatic and aliphatic terminal alkynes with various functional groups are tolerated under the reaction conditions.

  • 1549.
    Volla, Chandra M. R.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mazuela, Javier
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-Catalyzed Oxidative Carbocyclization-Carbonylation of Allenynes and Enallenes2014In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 25, p. 7608-7612Article in journal (Refereed)
    Abstract [en]

    A highly efficient oxidative carbocyclization-carbonylation reaction cascade of allenynes and enallenes has been developed using a Pd-II salt in low catalytic amounts under ambient temperature and pressure (1 atm of carbon monoxide). The use of DMSO as an additive was found to be important for an efficient reaction. A wide range of alcohols as trapping reagents were used to give the corresponding esters in good yields.

  • 1550. von der Lieth, Claus-Wilhelm
    et al.
    Ardà Freire, Ana
    Blank, Dennis
    Campbell, Matthew P.
    Ceroni, Alessio
    Damerell, David R.
    Dell, Anne
    Dwek, Raymond A.
    Ernst, Beat
    Fogh, Rasmus
    Frank, Martin
    Geyer, Hildegard
    Geyer, Rudolf
    Harrison, Mathew J.
    Henrick, Kim
    Herget, Stefan
    Hull, William E.
    Ionides, John
    Joshi, Hiren J.
    Kamerling, Johannis P.
    Leeflang, Bas R.
    Lütteke, Thomas
    Lundborg, Magnus
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Maass, Kai
    Merry, Anthony
    Ranzinger, René
    Rosen, Jimmy
    Royle, Louise
    Rudd, Pauline M.
    Schloissnig, Siegfried
    Stenutz, Roland
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Vranken, Wim F.
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Haslam, Stuart M.
    EUROCarbDB: an open-access platform for glycoinformatics2011In: Glycobiology, ISSN 0959-6658, E-ISSN 1460-2423, Vol. 21, no 4, p. 493-502Article in journal (Refereed)
    Abstract [en]

    The EUROCarbDB project is a design study for a technical framework, which provides sophisticated, freely accessible, open-source informatics tools and databases to support glycobiology and glycomic research. EUROCarbDB is a relational database containing glycan structures, their biological context and, when available, primary and interpreted analytical data from high-performance liquid chromatography, mass spectrometry and nuclear magnetic resonance experiments. Database content can be accessed via a web-based user interface. The database is complemented by a suite of glycoinformatics tools, specifically designed to assist the elucidation and submission of glycan structure and experimental data when used in conjunction with contemporary carbohydrate research workflows. All software tools and source code are licensed under the terms of the Lesser General Public License, and publicly contributed structures and data are freely accessible. The public test version of the web interface to the EUROCarbDB can be found at http://www.ebi.ac.uk/eurocarb.

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